The related applications describe and claim a power supply controller, and coupling of signals in such a controller, which can be used for controlling a plurality of isolating power supplies, such as switch mode power supplies or DC power converters and voltage regulators, for providing controlled electrical power to loads. For example, the power supplies may provide different supply voltages to various electrical circuits on a circuit card on which the power supply controller is also provided.
In such a power supply controller, separate IC (integrated circuit) control units can be provided on the primary and secondary sides of a transformer that serves to maintain an electrical isolation barrier between input and output sides of the isolating power supplies. The transformer conveniently provides for signal coupling in both directions between the primary and secondary control units, and also for power transfer from its primary to its secondary side to supply operating power to the secondary control unit and any related circuits (for example, a non-volatile memory) of the power supply controller on the secondary side of the transformer.
In embodiments of the inventions described in the related applications, the power supply controller and the signal coupling within it are arranged for controlling up to six power supplies. To this end, each of the primary and secondary control units has six converter state machines (CSMs), one for each of up to six controlled power supplies, as well as an input state machine (ISM) relating to an input or supply voltage.
Regardless of the particular number of, in this case six, controlled power supplies for which a power supply controller is designed, situations can arise in which it is desired to control a larger number of power supplies. It is therefore desirable to be able to provide a plurality of power supply controllers, hereinafter referred to as power supply controller units or PSCUs, for controlling larger numbers of power supplies.
However, a significant aspect of such control relates to sequencing of the controlled power supplies, for power-up and/or shut-down of the controlled power supplies in particular sequences and in accordance with monitored conditions relating to the controlled power supplies. To this end, it is desirable for all of the CSMs in different PSCUs to be informed of relevant conditions (including, for example, fault situations) of each other state machine. For a number of n state machines, this implies a network of n(n−1) signal paths among the state machines, and quickly becomes impractical with increasing n, i.e. an increasing number of controlled power supplies. Furthermore, such a network of signal paths is inconsistent with providing a small, integrated package form of the PSCU as described in the related applications.
Accordingly, there is a need to facilitate signal coupling among a plurality of units, such as PSCUs as described above, in a manner that can convey needed information without requiring an extensive network of signal paths.